The purpose of this work is to obtain further understanding as to the chemical, physical and biological properties of insulin, the antidiabetogenic hormone. In some investigations, parts of the hormone will be removed while in others amino acid residues will be added to the hormone in studies on the relationship of structural to biological activity. Investigation will also be conducted on a practical synthesis of insulin from the A and B chains. BIBLIOGRAPHIC REFERENCES: "Leucine Aminopeptidase (Bovine Lens): Effect of pH on the Relative Binding of Zn 2 ion and Mg 2 ion to and on Activation of the Enzyme" by Gregory A. Thompson and Frederick H. Carpenter, J. Biol. Chem., 251, 53-60 (1976). "Leucine Aminopeptidase (Bovine Lens): The Relative Binding of Cobalt and Zinc to Leucine Aminopeptidase and the Effect of Cobalt Substitution on Specific Activity" by Gregory A. Thompson and Frederick H. Carpenter, J. Biol. Chem., 251, 1618-1624 (1976).